Mutagenic activity of monochloramines and dichloramines in salmonella typhimurium

Mutagenic activity of ethanolamine mono-and dichloramines, histamine mono and dichloramines, and taurine mono- and dichloramines was studied in vitro using the S.tvphimurium strains TA 98 and TA 100. TA 100 was the most sensitive strain to mono-and dichloramines, and, when incubated the most active mutagens were ethanolamine and histamine dichloramines. Chloramines such as taurine mono or dichloramines were inactive. Glucose metabolism of the bacteria was critical to determine the mutagenicity. Chloramines were mutagenic when added to bacteria with glucose at 37°C, but killing predominated when chloramines were added at 4°C or 15°C, or at 37°C without glucose

Mutagenic and recombinogenic effects of the antitumor daunomycin

Daunomycin, one of the pyrrolo [1,4] benzo-diazepine antibiotics with potent antitumor activity, was tested for its effects on a number of genetic parameters. The results show that this antibiotic is nonmutagenic in the Ames strains of Salmonella typhimurium while mutagenic in only one and antimutagenic in the rest of the genes tested in the eukaryotic organism Saccharomyces cerevisiae. The antibiotic is, however, a potent recombinogen as it induced mitohc crossing over, mitotic gene conversion and, possibly other chromosomal alterations in a diplold strain of S. cerevisiae. These studies emphasize the need for a battery of test systems including eukaryotic organisms to detect the genetic activity of certain antitumor drugs

effect of the S9 liver fraction on the mutagenicity of N-methyl-N'-nitro-Nnitrosoguanidine and N-methyl -N-nitrosourea

The mutagenicities of MNNG and MNU in Salmonella typhijrium tester strain G 46 were examined. With increasing liver S-9 fraction from rats pretreated with Aroclor [R] 1254, the mutagenic activation of MNNG was markedly inhibited , taeas the mutagenicity of MNU was slightly increased. When MNNG or MNU was pre-incubated with liver S9 or liver microsojes for 10-15 min. At 37°C, the mutagenic activity was enhanced. Increasing the time of incubation longer than 15 min. decreased the mutagenic potency of MNU. This may be due to its instability at the elevated temperature

Assay of the mutagenicity of the carcinogens dimethylnitrosamine [DMN] and diethylnitrosamine [DEN] in salmonella typhimurium

The mutagenicity of DMN and DEN was assayed using Salmonella typhimurium TA 100. The mutagenic activation was detected by the pre-incubation of bacteria and nit-rosamine with liver S-9 fraction from rats pretreated with Aroclor 1254. A dose-response was seen both with increased amounts of nitrosamines and protein. The mutagenicity of DMN and DEN was significantly higher after pre-incubation at pH 6.0 compared with the pre-incubation at pH 7.2. However, the DMN demethylase activity decreased as the pH was lowered. Therefore, the demethylase activity is inversely correlated with the mutagenic response